I'm putting the questions on top to make them easier to read on your gps.
- There are two types of wetland marshes at Sea Center Texas. What are the two types?
- Give a brief description of the differences you see in each type of marsh. Please do not send just a dictionary or wiki description of the marsh types. Tell me specifically what it looked like the day you were there.
- Why did Sea Center Texas create these marshes?
What is a Wetland?
Wetlands are the transition zones between land and water. They are hard to define because of their great variation in size, location, and human influence. To be defined as a wetland three main components must be included: 1) Wetlands must have water present, either at the surface or within the root zone, 2) wetlands must have unique soil conditions that differ from the adjacent upland, and 3) wetlands must support water tolerant plants (hydrophytes).
Hydrology
Hydrology is related to a wetland in the sense that it supplies the area with the water to affect the soil and plants present in the area. The hydrolic conditions affect both the abiotic and biotic condition of the wetland. Abiotically, water affects the soil gas content (and eventually the biotic levels), nutrient availability, and in coastal wetlands, the salinity. Biotically, the water affects the life in and around the wetland. The sources and availability of water in a wetland are continuously changing. Tides, periodic storms, seasons, floods, droughts and many other factors affect the water level of a wetland. The source of water for a wetland can come from ground water, precipitation, and for coastal wetlands –ocean tides, just to mention a few.
Hydric soil
Hydric soils are soils that have been saturated long enough during the growing season to create anaerobic (low oxygen) conditions in the top layers of the soil. Chemical transformations and primary storage for the nutrients needed by the wetlands plants take place in the hydric soil. Soil from wetlands can be classified either as organic or mineral soils, depending on the amount of organic matter present. These soils’ physical and chemical characteristics affect several features of wetlands, including the ability to hold water, nutrients and to trap pollutants. Hydric soil has many distinguishing characteristics such as a sulfurous (rotten egg) smell; brown, dark gray or black soil; soil having a wet feel and a mottled color.
Hydrophytic Plants
Hydrophytic plants have adapted to survive in wetlands despite the stress of an anaerobic and flooded environment. Unlike common land plants that are able to get oxygen directly into their roots, the hydrophytes have internal oxygen-transporting tubes, the ability to float on shallow water or buttressed trunks to take oxygen down to the roots of the plants. These plants are often the first and most important indicators of a wetland.
There are several plant adaptations that help capture and transport oxygen to other parts of the plants. For example, tree roots may jut out of the ground (such as Black Mangrove) and extend above the low tide line allowing oxygen to get directly to the exposed roots. Some hydrophytic plants have exposed or shallow roots to pick up the small amount of oxygen from the soil surface. Other plants have hollow tubes or sacs that transport oxygen to the roots. Buoyant plants have root systems that dangle in the water, providing access to oxygen that is mixed in the water. All these adaptations help the plants to survive in a habitat that no land plants could survive in.
Difficulties of Defining a Wetland
Many factors affect the distribution of wetlands across the United States and the world. As seen by the hydrology, hydric soil, and the variety of plants, the smallest change in the system can drastically change the entire wetland. Existing wetlands are affected by seasonal fluctuations in precipitation, low-lying topography that collects surface water, draining properties of soils in the considered area, temperature which can affect evaporation and plant growth and much more.
Even though these are fairly straight forward components, combining them to make one general definition is difficult because components vary from wetland to wetland, and, more importantly, the three variables are not independent of each other. Each wetland’s hydrology, soil, and plants vary from season to season and from year to year, making it hard to define strict boundaries of any wetland. Each wetland also has its own unique hydrology, soil and plants according to its location. In addition, defining a wetland is subject to individual or professional interpretations. Thus a geologist, hydrologist, biologist or ecologist will each define a wetland according to their professional frame of reference making a common definition even more difficult.
Functions of a Wetland
Flood control, storm buffers, soil stabilization, nurseries and habitats for various species are just a few of the important roles that wetlands play. Wetlands have the ability to store flood waters and then slowly release the stored water, reducing the impact of floods. By storing the flood water, it reduces the velocity
of floodwaters, reducing the amount of damage caused by the runoff.
Along with reducing the velocity and stage of the flood water, some of the stored water seeps into the ground, recharging the aquifer. The wetlands ability to recharge the groundwater is dependent on the soil permeability, porosity, wetland size and local geology. The soil permeability and porosity affects how fast the water can be moved through the earth to the aquifers. If the permeability and porosity are high, then more water can be moved more quickly into the aquifer than if the permeability and porosity are low. The< size of the wetland also has an effect on the recharging of groundwater, because the greater the boundary area between land and water, the more water that can be moved to the aquifer.
Wetlands along the coast such as coastal marshes and mangrove swamps can act as effective storm buffers. The roots of the wetland vegetation hold the soil in place and their stalks and leaves reduce the destructive energy of the waves, allowing more sediment to be collected. The collection of sediments
increases the area of the wetland, making it a more effective storm buffer.
Wetlands account for a tremendous amount total global productivity primary productivity (24 percent),
and as a whole they out-produce almost all other ecosystems. This primary productivity derives from all the vegetation that has the ability to photosynthesize and creates diverse habitats that play an important biological role. Their biological productivity attracts wildlife, which utilize the wetlands for food, nesting, spawning, predatory opportunities and shelter.
Image courtesy of www.earthgauge.net.
The Wetlands at Sea Center Texas
In the past wetlands were looked upon as wastelands and until the 1970’s, drainage and destruction of wetlands were accepted practices. Since people have gained a better understanding of wetlands and how they benefit the environment, today’s view is quite different. Currently, the government is following a no-net-loss policy: If any wetland is destroyed then a similar wetland must be created in its place. Sea Center’s hatchery ponds and facilities were built over existing wetlands, destroying them; therefore the wetland exhibit was created to compensate for this loss. To lessen or compensate for such impact caused by construction is called mitigation.
Even though wetlands are hard to define because of the variations among the hydrology, hydric soil, and hydrophytic plants, since the 1970’s most people have recognized that wetlands protection is important. Many important functions including recharging ground water, nurseries, and habitats, and building or enhancing already existing wetlands are observable at Sea Center Texas. Youth and the public at large can learn about the importance of wetlands to all aspects of the environment.